Hmm... been sitting on an iMac 27" since early 2011 and it's been great. I've managed to crash it only twice because I tried to delete corrupt files (my bad), but other than that I just can't get the thing to lock up or not do something, so its definitely been stable as a workstation.
Screen is really, really good, even out of the box; I mean reference-grade stuff. Lack of upgrades seemed like a downer at first, but looking back, technology went by so fast that I always ended up buying new computers every 5-8 years or so, since the entire mobo/cpu/ram architecture would change by then. Extra data I handle with external storage which makes sense in my particular case, because I can physically move data around that I need to do often, and an extra TB or two is just a couple hundred bucks.
Since I actually use my computer for real work, price wasn't much of a consideration, as it's payed itself back many times now by not crashing.
YMMV.